(i) Field of the Invention
The present invention relates to geared transmissions that have use on road and off-road vehicles, in machinery and other drive applications, where there is a need to alter either the output torque, or output velocity of the prime mover in small incremental steps.
(ii) Description of the Prior Art
Transmissions presently available, such as so-called "automatic" and "manual" automotive transmissions and machinery drives, are generally considered wide ratio transmissions because the change in their gear ratios are in relatively large steps. Although some close ratio geared drives are presently available they are relatively large and expensive. The reason for this is that the number of ratios available is almost directly related to the number of gear sets in the transmission. The following patents reflect this state-of-the-art methodology of effecting ratio changes:
U.S. Pat. No. 338,339, A Variable Speed Power Transmission System, Jan. 17, 1964. PA0 U.K. Pat. No. 958,922, Ratio-Selector Device for Epicyclic Gear Boxes, May. 27, 1964. PA0 U.K. Pat. No. 1,114,186, Epicyclic Gearing, Dec. 21, 1965. PA0 U.K. Pat. No. 1,144,456, Epicyclic Toothed Gearing, July 28, 1966. PA0 U.K. Pat. No. 1,525,593, Planetary Change-Speed Gear, Sept. 20, 1978. PA0 U.K. Pat. No. 1,082,751 Improvements Related to Gears, Sept. 3, 1976. PA0 U.K. Pat. No. 1,248,119 Inprovements In or Relating To Gear trains, Sept. 29, 1971. PA0 U.K. Pat. No. 1266850, Free-floating Planetary Transmission, Mar. 15, 1972. PA0 U.K. Pat. No. 1418284, Planetary Gear, Dec. 17, 1975.
In the above mechanisms the gear elements are either in, or out, of continuum, with each gear set, or combination of gear sets, providing only one of the specific ratios of the transmission.
The following patents reflect the state-of-the-art cageless epicyclic gear trains, and are in some ways related to the structure of the cageless planetary gear trains of this disclosure.